Shank piece for shoes



R. P. SCHWARTZ SHANK PIECE FOR SHOES June 26, 1951 5 Sheets-Sheet 1 Filed Nov. 18, 1946 INVENTOR.

llulll June 26, 1951 3 Sheets-Sheet 2 Filed Nov. 18, 1946 June 26, 1951 R. P. scHwAR-rz 2,558,317

SHANK PIECE FOR SHOES Filed Nov. 18, 1946 3 Sheets-SheetI 5 Patented June 26, 1951 UNITED `STATES PATENT OFFICE sHANK PIEcEFoR snoEs Russell Plato Schwartz, Brighton, N. Y. Application November 18, 1946, Serial No. 710,708

(C1. `ses-'16) 2 Claims. 1

This invention relates to shoe construction and the application of precision methods to the making of shoes, with particular reference to shoes described in my Letters Patent No. 2,160,991 and herein referred to as functional shoes.

One object of the invention is to assure uniformity of construction of functional shoes by automatically providingcorrect curvatures and exact positioning of the parts so as to permanently retain the intended shape and alinement. Y Another object is to provide an improved functional shoe of more accurate and uniform shape, to maintain anatomically correct foot function and to relieve the shoe and foot of strain resulting from structural derangemcnt.

Another object is to provide such a functional shoe with an insole having the foot engaging surfaces of its heel and shank portions molded in precise conformity with the corresponding surface portions of the last on which the shoe is made, so as to afford a maximum degree of accurate foot support and-control.

Further objects of this invention, equally applicable to shoes of functional or conventional design, are to supply a shoe construction insuring uniformly precise positioning of the shank piece and insole relatively to the lastand to each other; provide footwear of a more durable nature by removing strains due to improper tread, eliminating internal wear due to slipping between the parts and providing a lighter and more stable shank piece with less tendency to cut the leather; provide a shoe having longer life and lower cost of construction; simplify shoe construction by reducing the number of parts and facilitating the convenient and accurate-assembly thereof, and also to provide a more practical, rapid and economical method of making shoes having the above characteristics and advantages.

To these vand other ends the invention resides in certain improvementsV and combinations of parts, al1 as will be hereinafter more fully described, the novel features Abeing pointed out in the claims at the end of the specification.

; In the drawings:

Fig. 1 is :a central, longitudinal, sectional elevation of the bottom portion of a shoe of the cemented type, embodying the present invention, and shown in inverted position ona last;

,.Fig. 2 is a planview as seen from the top in Fig.- 1 and showing a shankpiece and insole positioned on a last; l

(Fig. 3 is a sectional elevation of the shoe on the line 3`3 in Fig. 1, but .with the parts in upright Position; 1 Y

Fig. 4 is a view similar to Fig. 3, taken on the line 4 4 in Fig. 1; l Fig. 5 is a View similar to Fig. 3, but taken on the line 5 5 in Fig. l;

Fig. 6 is a top plan view of a shank piece em ployed in the shoe;

Fig. 7 is a sideelevation of the same, as viewed from the lower edge in Fig.6;

Fig. 8 is a top plan view'of an insole employed in the shoe;

Fig. 9 is a sectional elevation on the line 9-9 in lig.` 8, and 5 Fig. 10 is a view similar to Fig. 4, but illustrating the application of the invention to a welt shoe.

In the manufacture of shoes, the sole portions are generally lasted on the curving surfaces of the last bottom and, in addition to the difficulties of conforming them to these curvatures during the manufacturing operations, they tend in time to warp and return to initial shape, with the result that these foot supporting portions of the shoe often fail to accurately conform to the intended last shape for properly supporting and controlling the action of the foot.

Furthermore, in the rapid methods currently employed in the manufacture of shoes of the known types of construction, the insole is commonly located and alined on the last by reliance upon the operators fingers and sense of feel as a guide. In view, however, of the 'indefinite curvatures of the last bottom, this method of positioning the insole is subject to considerable' variation with the individual operator and between dilferent operators, and such variations in the placing of the insole interfere with precision and uniformity in the shaping and construction of the shoes.- An example of such defects may be seen in the tendency of conventionally designed shoes to rest on the sole and the breast points only of the heel, the back line of the heel being elevated from 1/8 to 1%; of an inch from the level floor surface while the shoe is free from Weight. With weight bearing, the back part of the heel is forced into contact with the floor, thus straining the entire shoe over the fulcrum of the breastpoints, this defect being the result ofimproper positioning of the shank and its failure to conform accurately to the last contours.

I have found that such defects in manufacture and in the support and control of the foot, particularly in functional footwear, are overcome by a new method of manufacture and construction comprising a shank piece molded of plastic material, `so as to faithfully reproduce and permanently maintain a mirror image of the last, with l 3 all of its intended characteristics of shape and function, this shank piece, furthermore, being positioned above, rather than below the insole, so as to more closely engage and more accurately support and control the foot.

Referring to the drawings for a more particular description, there is shown in Fig. 1 a shoe embodying the present invention in inverted position on a last l5,V the bottom surfaces of which may have any desired functional or conventional shape and curvature, exceptthat on conventional lasts I provide its metal nailing plate I6 with two or more spaced projecting parts, or dowel-like pins I1, for interengagement with cooperating depressions or sockets in the novel shank piece of my invention, which will now be described.

My novel shank piece is preferably made of plastic materialY having an upper surface molded directly to and faithfully conforming with the bottom surfaces of a last-corresponding in shape to that on whichV the shoeV is made. This shank piece I8 (Figs. 1, 2, 6 and 7) is preferably substantially coextensive in area with the heel and shank portions of the inside of the shoe, extending in full width from the back of the heel forwardly adjacent the ball or metatarsal portion of the foot, as shown. For use with conventional lasts the upper surface of the shank piece, which is placed against the last bottom, is formed with depressions or sockets I9 to closely t the dowels l1 of the lastand quickly and precisely locate the shank piece on the latter. The bottom of a functional last has suicient curvature to provide positive location of the counter molded shank piece so as to usually obviate the dowels IT and sockets I9 preferred with conventional lasts, although it will be understood that such dowel locating means may be employed wherever found desirable. The shank piece has sufficient thickness to afford the desired strength and stiffness, varying from point to point to conform with, the curvature of the last and provide the desired contours on its upper or foot supporting sur,- face. The forward end of the shank piece (Fig. 2) is preferably extended forwardly and curved, as shown, to conform with the location of the metatarsal portion of the foot, and I prefer to taper off and incline the shank piece edgesupwardly, as shown, for smooth continuity with the upper portions of the shoe, its edge, being carried well up under the inside waist of the shoe.-

Such a shank piece, in` view of its? molded construction, is `adaptableto a variety of shapes, being well suited, for example, for carrying out the Yfunctional principles of the shoe disclosed. and claimed in my Letters Patent No. 2,160,991, and for use with such a shoe the thickness and the height of the inner surface of the shank piece, along the inside of the heel of the shoe, are increased, as shown at 2| in Fig. 5.

The outer or lower surface of the shank piece is formedv with two or more projecting parts, preferably in the nature of dowel-like pins, 22, for engagement in cooperating recesses in the upper surface of the insole hereafter described, these pins being conveniently formed as integral projections in the molding of the shank piece, which may be molded of known ,and suitable plastic materialsl such, for example, as methyl methacrylate, nylon, or the like. I preferably employ a material which, on curing, acquires a substantially rigid character.

'Ihe insole 23 of my shoel is preferably substantallylcoextensive in size and shape with its 4 Y bottom and may be made of any desired thickness of leather, composition or other known material. It is formed with recesses or sockets 2l closely fitting the dowel pins 22 on the lower surface of the shank piece, with which these insole sockets are engaged for locating and aligning the insole relative to the shank piece and the last. The insole and the shoe may be made in any desired type of construction, such as a cemented or welt shoe. For the cemented shoe construction, shown in Figs. 1 to 9, inclusive, of the drawing, the peripheral edge of the lower surface of the insole is preferably channeled as at 25, for the reception of the lasted edges 26 of the usual upper portions 21 of the shoe, although the lasting of thesev parts may be accomplished in other known ways,L as well understood in the Vart". An outsole 28 is cemented to the bottom of the insole in known ways and is provided with the usual or any suitable heel 29.

1 In the manufacture of shoes embodying the present invention, the shank pieces areV con-l structed as described and molded of one of the described materials, by any known or suitable molding apparatus and method, one side of the mold conforming precisely in contour with the bottom of the heel and shank portions of the last on which the shoes are to be lasted. The shankV pieces having been cured and set to a stiff and preferably to a substantially rigid condition,

are quickly and precisely applied to the bottom of the last, aided, in the case of conventional shoes, bythe locating engagement of the depressions |9 with. the dowel pins I1 of theA last bottom. The insoles, made as described with the sockets 24, are quickly and precisely located on the shank piece and the. bottom of the last, the interfaces between the insole and shank piece being supplied with cement and the insole being thereby firmly cemented to the bottom of the shank piece. The upper portions are then drawnV over the last and cemented or otherwise secured in the channel of therinsole, as well understood in the art, after which the outsole and heel are l applied inthe usual, or any known or suitable fashion. The accurately molded upper surface describedv abovedescribed as adapted to cemented and welt'con-v Y lof the shank piece, is thus arranged for direct -engagement with the foot of the wearer, to accurately support and control it, although, if desired, alight sock lining may be inserted in the shoe without materiallyv interfering with its described functions. Y

In Fig. 10 is shownV a modified construction in which the-,invention is adapted for use in combination with a shoe of the known welt construction. This figure is similar to Fig.v 4 except that the insole 39 is channeled: to form a lip 3| to which are secured, as by means of the. stitching' 32, the upper portions 33 of they shoe and a WeltY structions, it is obviously applicable to other types of shoes as well.

It is evident that the invention provides a` simple and practical shoe construction requiring a minimum number of parts, as well as a prac` ticaland economical method of manufacture. Since the plastic shank piece is a precisely moldedn reproduction of the bottom of the last itself, all4 last characteristics are reproduced in the highest degree, thereby assuring maximum foot support and control. Such precision molding of the plastic shank piece insures correct curvature and exact placement of the parts, and the shoe and foot are relieved of the strains resulting from excessive breast point pressure. The improved supportand control of the foot likewise reduce both shoe and foot strain and contribute to a more uniform distribution of the forces applied to the shoe incident to weight bearing. At the same time, the internal wear on the shoe is reduced, through elimination of slippage by the dowel attachment of the shank piece and insole. The initial shape of the shoe is more faithfully retained throughout its life because the plastic shank piece does not change under the influence of body heat, moisture or pressure, and such shank pieces are lighter in weight with less tendency to cut the leather than metal shanks. The meansprovided for rapidly and accurately locating the shank piece and the insole relative to the last and to each other eliminate guess work and simplify and expedite the manufacturing operations, with reduction of defective work and Waste and of the cost of production generally.

It will thus be seen that the invention accomplishes its objects and while it has been herein disclosed by reference to the details of preferred embodiments, it is to be understood that such disclosure is intended in an illustrative, rather than a limiting sense, as it is contemplated that various modications in the construction and arrangement of the parts will readily occur to those skilled' in the art, within the spirit of the invention and the scope of the appended claims.

I claim:

1. A shank piece for use in the manufacture of shoes, said shank piece having its inner surface formed with a curved shape which is a counterpart of the bottom surface of the heel and shank portions of a last and provided with locating means for engagement with cooperating locating means on said last surface for accurately locating said shank piece thereon, and said shank piece having an outer surface adapted to have an insole secured thereto and provided with locating means for engagement with cooperating locating means on said insole for accurately locating said insole on said shank piece and last in position for the lasting of a shoe thereon.

2. A substantially rigid shank piece for use in the manufacture of shoes, said shank piece being made of moldable material with its inner surface having a shape which is a counterpart of the curved bottom surface of the heel and shank portions of a last and provided with locating means for engagement with cooperating locating means on said last surface for accurately locating said shank piece thereon, and said shank piece having an outer surface adapted to have an insole secured thereto and provided with locating means for engagement with cooperating locating means on said insole for accurately locating said insole on said shank piece and last in position for the lasting of a shoe thereon.

RUSSELL PLATO SCHWARTZ.

REFERENCES CITED The following references are of record in the le of this patent:

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